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1 톤급 양산형 진공 침탄로에서 아세틸렌 유량과 로 내 위치에 따른 AISI 4115 강의 침탄 거동
권기훈 ( Gi-hoon Kwon ),문경일 ( Kyoungil Moon ),박현준 ( Hyunjun Park ),이영국 ( Young-kook Lee ),정민수 ( Minsu Jung ) 한국열처리공학회 2021 熱處理工學會誌 Vol.34 No.6
The influence of acetylene flow rates on the carburizing behavior of an AISI 4115 steel in 1 ton-class mass production-type vacuum carburizing furnace has been studied through microstructure, carbon concentration, hardness analyses. The AISI 4115 steels were carburized with various flow rates (20, 32.7, 60 l/min) and locations in the furnace (top, center, bottom) at 950℃. The acetylene flow rate played an important role in controlling the carburizing properties of carburized samples, such as effective case depth and uniformity carburizing according to location in the furnace. At an acetylene flow rate of 20 l/min, the carburized samples had a shallow average hardened layer (0.645 mm) compared to the target hardening depth (1 mm) due to low carbon flux and spatial uniformity of carburization (17.8%) in the furnace. At a flow rate of 60 l/min, the carburized samples showed an average hardened layer (1.449 mm) deeper than the target hardening depth and had the spatial uniformity of carburization (98.8%). In particular, at a flow rate of 32.7 l/min, the carburized samples had an average hardened layer (1.13 mm) close to the target hardening depth and had the highest carburizing uniformity (99.1%). As a result, an appropriate flow rate of 32.7 l/min was derived to satisfy the target hardening depth and to have spatial uniform hardened layer in the furnace. (Received Septemer 16, 2021; Revised Septemer 28, 2021; Accepted October 8, 2021)
Cu 첨가가 Mo-Cu-N 코팅의 미세구조와 기계적 특성에 미치는 영향
김수빈(Soobyn Kim),윤혜원(Hae-Won Yoon),이한찬(Han-Chan Lee),문경일(KyoungIl-Moon),홍현선(Hyun Seon Hong) 한국표면공학회 2019 한국표면공학회지 Vol.52 No.4
Mo-N based coatings have been studied for enhancing mechanical characteristics of thin films. In the case of Mo-X-N coatings, the microstructure and mechanical properties can be affected by the addition of the third element. In this work, Mo-Cu-N coatings were successfully fabricated with varying the Cu content from 4.5 at% to 31 at% by the co-sputtering method. Thus, properties of the coatings were analyzed by EDS, SEM, XRD, AFM, nano indentation and scratch test techniques. From observed results, MoxN bonds were made in a nitrogen atmosphere and Cu elements were present at grain boundaries. In addition, coatings with the Cu content above 14 at% had a Cu3N peak in the XRD results. Thus, it is suggested that the formation of Cu3N phase affected the microstructure and mechanical properties of Mo-Cu-N coatings. Mechanical properties of Mo-Cu-N coatings were found to be relatively better at Cu content of about 12 at%.
Cr-Mo 저합금강의 진공침탄 공정 압력 및 질소 첨가 비율에 따른 경화깊이 균일도 및 표면 특성 효과
권기훈(Gi-hoon Kwon),박현준(Hyunjun Park),안기원,이영국(Young-Kook Lee),문경일(Kyoungil Moon) 한국표면공학회 2023 한국표면공학회지 Vol.56 No.1
The effects of carburizing pressure and gas ratio on vacuum carburizing properties (uniformity and surface characteristics) have been studied through the analyses of carbon concentration, hardness, surface color, surface roughness and type of carbon bonding. AISI 4115 steel specimens were carburized with various pressures (1, 5, and 10 Torr) at different locations (P₁, P₂, P₃, P₄, P<SUB>5</SUB>, and P<SUB>6</SUB>) inside a furnace held at 950 ℃. Since the carburizing pressure represents the density of the carburizing gas, it plays an important role in improving the carburizing uniformity according to locations in the furnace. As the carburizing pressure increased, the carburizing uniformity according to the sample location was improved, but the surface of the carburized specimen was discolored due to the residual acetylene gas, which does not contribute to the carburizing reaction. Therefore, the carburizing uniformity and surface discoloration have been improved by injecting acetylene gas (carburizing gas) and nitrogen gas (non-reactive gas) in a specific ratio.